Transmission of audio and video signals to local receiving stations for immediate use, rebroadcast, or recordation for later broadcast is well-established practice, particularly in connection with distribution of television programming by various television networks. Use of data to generate characters which are displayed on a video screen over a single color background or another video signal background is also established practice.
However, expansion in the availability of data of both general and specific interest to various groups of data consumers and need for a system capable of efficiently transmitting such data to specific remote locations and to control the further broadcast, display, or transmission of such data at those locations have resulted in the need for audio, video, and data transmission systems with associated control capabilities not previously available.
U.S. Pat. No. 4,725,886, related to the present application as noted above, discloses and claims communications systems utilizing a novel hardware and software configuration simultaneously to transmit conventional video and audio program material together with data and control commands within the constraints of conventional television signal specifications to remote signal processors or receivers within the system. The remote signal processors or receivers receive the entire transmission and process it in a predetermined manner such that the data and the conventional video and audio signals may be utilized at the remote receivers, under network control, particularly for broadcast on local cable television systems.
These systems transmit, typically utilizing a satellite transponder, a first conventional video and audio television signal together with a digital data stream transmitted in the vertical blanking interval of the first video signal, or a subcarrier frequency or as otherwise appropriate. The data stream comprises digital control, address, and text data. A local unit may process and retransmit the first video (and audio) signal and, utilizing a character generator, store the digital text data and process it into a second ("satellite" text) video signal containing text for retransmission. In addition, the unit may receive and retransmit a third video (and audio) signal from a local source such as a video recorder, so that local commercials or other material may be displayed, and it provides a synchronization signal which may be input to the local source to synchronize signals from it with other video signals processed or generated by the unit. So that local cable operators may also be able to compose and display textual data, the unit may also receive digital data from a keyboard. This data, as well as data from local weather sensors, is processed by the unit into a fourth video signal containing text. On command from network control, the unit may select for output the first satellite video (and audio) signal, the third local video (and audio) signal, or a solid color background video signal, and may combine with any of these signals the second (satellite) and/or fourth local textual video signals.
The digital control and address data in the data stream of the first video signal control the operating states, or modes, of such units and determine the video, audio, and other outputs of a particular unit. Control data sent in the "Output Mode Control Word" ("OMCW") of the data stream determines, among other things, which video signals or combinations thereof will be presented and which audio signals will be presented, by controlling whether satellite video, local video, or character generator input will be processed and sent by the unit.
The address words of the data stream and the control words following them allow each such unit or a group of units to accept, store, and process particular text data and to display this text in a particular format. Thus, different digital text data may be stored by different units in groups of units for simultaneous presentation in response to the OMCW control data which controls timing of such presentation. Groups may be organized into higher level groups, so that these systems allow simultaneous control of units in a hierarchy of groups.
Units disclosed in U.S. Pat. No. 4,725,886 may be utilized for a network of local affiliates receiving transmissions from a single source dedicated to television programming related to weather information and advertising, financial data, sports, or other programming. Accordingly, the hierarchy of addressability utilized in embodiments disclosed in that document contemplates geographic organization of local units consistent with weather patterns. That document emphasizes, however, that the invention may also be adapted for transmission of entirely different programming and data for other types of commercial broadcasting and for non-commercial communications, including teletext-only communications, and aspects of the invention may be adapted to other uses such as various remote control networks.
A plurality of such units can be organized and addressed hierarchically for purposes of receiving and processing satellite video and teletext data according to a hierarchical address structure of four sub-fields: Service, Zone, County, and Unit. The address of a unit is set by positioning switches in the unit. The unit compares or matches sub-fields in addresses of received data one sub-field at a time to determine whether messages are addressed to it.
It has recently become useful, however, to arrange and control classes of units not necessarily according to geographical location or a hierarchical structure, but according to other criteria such as, for instance, a certain market such as a metropolitan area comprising portions of several counties or zones. Advertisers appreciate this capability as well as viewers who wish to receive the same information as others in their area without discrimination according to geographic boundaries or other hierarchical structures. Pending U.S. application Ser. No. 07/323,089, related to the present application as noted above, supplements the capabilities of the unit disclosed and claimed in U.S. Pat. No. 4,725,886 by allowing units to be controlled according to preselected classes independent of their hierarchical address structures. This additional capability results from changes to software in the units and the structure of data sent to them, as disclosed more fully in the specification of that application.
Other additional capabilities according to the invention disclosed in application Ser. No. 07/323,089 are the ability to cause units to enter into a "Crawl Alert" mode or state with satellite video and audio and with a solid color background in the bottom region of the screen across which messages may crawl, accompanied by intermittent audio signals. The invention also allows units to display remotely collected weather observations, such as those from local meteorological offices, if they sense loss of connection with their corresponding temperature probes, and to display crawl text corresponding to weather warning information stored in RAM. The invention further allows for the rainfall counter circuits to be easily reset or updated from the unit's keyboard.